This page has several ways for programmers to get started with Squeak.
For non-programmers, see Squeakland.
For WebWareWriters, see Seaside, it'll change the way of your Squeak life;) It's well documented and easy to learn. (–Jigme, China)
Introductory Squeak - Some basic aspects of Squeak & Smalltalk explained as an intro to a computing course given at the University of Canterbury, NZ (last updated around 1999!)
Terse guide to Squeak - a condensed overview of Squeak language and features, useful as an aide-memoirs (could do with updates; block temps etc have changed)
Various tips from Mark Guzdial, author of a text book based on Squeak. (last updated around 1998!)
Notes and lecture slides on the Squeak environment from University of Washington's undergraduate programming languages course. Targeted towards getting you coding quickly. Assumes you have a supplementary text or instructor to teach you the Smalltalk language properly.
Squeak Help by Maarten Maartensz, who doesn't believe in Swikis.
EasySqueak A package to develop Squeak training materials
Squeak MVC Tutorial (MVC is not really relevant for most beginners, but certain sections such as about the language, processes, exception handling, or Encyclopaedia of Classes are still relevant)
Exercises
Ultimately, to learn Smalltalk, you have to spend some time programming in it. The below exercises make terrific practice.